Chromium-plating machine



Oct; 15, 1929. w; s, EATON 1,731,456

! v CHROMTHM PLATING MACHINE Filed 001;. 28, 1926 2 Sheets-Sheet 1 Oct.15, 1929. w, s, EATON crmom um PLATIING mourns 2 Sheets-Sheet 2 FiledOct 28, 1926 INVENTOR OOOOUJOOOOGOOKV O w w A 5.. w w fl J4- Wu 52 BY W/Z A'lTORNEY Patented Oct. 15, 1929 UNITED STATES WILLIAM S. EATON, OFSAG HARBOR, NEW YORK CHROMIUM-PLATING MACHINE Application filed October28, 1926. Serial No. 144,678.

My invention relates to chromium plating machines, and more particularlyto a construction and arrangement of parts which will present, incompact form, all of the agencies required in carrying on the platingoperation under conditions which will avoid likelihood of injury to theuser of the machine.

With a machine embodying the invention, the plating operations may beperformed by labor having little or no technical knowledge of therequirements ofchromium plating,

the operation of the machine requiring merely the observance of simplerules, substantial deviation from which will have no injurious eflectupon the operator, upon the machine, or upon the article being plated.

The machine illustrated in the accompanying drawings is particularlydesigned for applying a chromium surface to printmg plates, the machineincluding therein a holder for such plates so constructed as to permitthe plating of a single or a plurality of plates simultaneously. Thisholder is not only so constructed as to facilitate the mounting ofplates thereon and their removal therefrom, but the shifting of theholder, in its entirety, from one tank to another when required duringthe plating operation. During the depositing of chromium, the holder andthe plate or plates carried thereby form the cathode of an electrolyticcell, my invention contemplating a construct-ion of the holder by whichthe surface upon which the chro mium is to be deposited is limited tothe plate within the holder no substantial areas of the holder itself,exposedhtoward the anode, being of electro-conductive material.

Not only does a machine embodying the invention include those agenciesby means of which a plate may be prepared for the electro depositing ofchromium thereon and the depositing of such chromium, but also agenciesby means of which a previously applied surface of chromium may beremoved from an article, as when, assuming the article to be a printingplate, wear has occurred upon the surface to an extent to make are-plating thereof desirable.

The tanks containing the various solutions for cleaning, washing,plating or stripping a plate are not only so arranged in relation toeach other as to permit the withdrawal of a plate holder from onesolution and its submersion in another, but are supported at a height topermit a convenient handling of the holder. A movable closure for thespace above the tanks is provided, so that the operator may have freeaccess to any tank or be protected from gases or fumes evolved duringthe plating operation, such being withdrawn from the housing above thetanks as rapidly as they are evolved. Hence when the closure is moved toexpose the tanks following the completion of the plating operation, nofumes will escape from the machine.

, I also provide in the machine, a special mechanism for connectingmetallic chromium anodes to a bus bar.

The invention consists in the novel features of construction andcombination of parts hereinafter set forth and described, and moreparticularly pointed out in the claims hereto appended.

Referring to the drawings,

Fig. 1 is a front perspective view of a chromium plating machineembodying the invention, with the parts in a position to permit the userto ship the plate holder to the required tank, the door being in theopen position, partly broken away;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 1

Fig. 4 is a front elevation of the holder for the plate or otherarticle;

Fig. 5 is a side view thereof;

Fig. 6 is a diagram illustrating the electrical conditions in themachine; and

Fig. 7 is a detail view of the anode support.

Like numerals refer to like parts throughout the several views.

A chromium plating machine embodying my invention contains four tanks10, 11, 12 and 13 arranged side by side within a supporting angle metalframe 14, at a height to position the open tops of said tanks so thatthe operator may conveniently place a plate holder within any tank orremove it t erefrom as required during different stages of the platingoperation.

, The portion of the frame above the open tops ofthe tanks is closed bymeans of the side plates and 16, the back plate 17, a top plank 18 and adoor 19 hinged to a brace 20 servingnot only as a support for this door,but as a lateral brace for the frame 14.

The frame 14 afl'ords corner braces serving as legs for supporting themachine, the frame being further braced by laterally extended anglemetal braces 21 and angle metal top braces 22 extending entirely aboutthe top of the frame, and supporting the top plank 18. Passingthroughthe plank 18 is the intake pipe 23 of an exhauster 24, the outletof which exhauster may be connected with a flue leading to, or directedtoward an opening communicating with atmosphere. This exhauster ismotor-driven and preferably is so wired as to be set in operationsimultaneously with the closing of the circuit to the electrodes,whether during the operation of cleaning, plating or stripping, duringwhich operations the door 19 will be closed. Hence all gases and fumesevolved as a result of electrolytic action within the machine will becarried away from the upper portion of the machine so that possibilityof the escape of noxious fumes within a workroom, or into the face of anoperator upon the opening of the door 19, is prevented. The use of thedoor 19 also prevents an operator from leaning over the tanks during theplating operation, with resultant irritation of the membranes of thenose and throat resulting from the inhalation of chromic acid fumes. Thequantity of hydrogen freed during the electrolytic action is notsufliciently great to introduce fire hazard. The space below the plates16, 17 and 18 and brace 20, and between the lower edges of these platesand said brace and the various tanks, will permit the effective actionof the exhauster.

The tanks 10, 11, 12 and 13 are supported by means of insulatingmaterial from T-irons 25 extending laterally of the machine andconnected with the back and the front legs of the frame 14, theinsulating material consisting of a board 26 upon which the tanks rest.

Said tanks are also insulated from each other by means of headedinsulating slabs 27 suspended from the top side edges of adjacent tanks.These insulating slabs not only serve as insulators between therespective tanks, but as insulating supports for a bus bar 28 supportinga carbon electrode 29 in the tank 10, and chromium metal electrodes 30in the tank 12, thus effectively insulating this bus bar from the tanks,and permitting its adj ustment with relation to the front walls of thetanks 10, 12 and 13.

The tank 10 is lined as to the side walls,

thereof with insulating material such as glass plates indicated at 10the insulation of the bottom of the tank not being required because forthe back wall, since this wall is used as a cathode during the strippingoperation as will more fully appear hereinafter.

The manner of mounting the several tanks is such as to maintain theouter walls thereof out of electrical connection with the supportingframe 14.

The cathode of the electrolytic cell during the cleaning and depositingoperation in the tanks 10 and 12, and the anode during the strippingoperation in the tank 14, consists of a plate holder so constructed asto be hung within said tanks with relation to the foroperator, theeffective insulation of said holder from any of these tanks being se-'cured by means of a slab of insulating material, 10 12 13 insertedbetween each tank and the adjacent portion of the frame 14, these slabsbeing held in position by the insulating slabs 27 between the tanks, andextending above the top edge of the tanks to an extent to space thesupporting member of the holder away from the metal of the tank at thispoint. his construction has the advantage that when the holder isslipped within the tank, it will be supported from the insulating slababove referred to, and the back of the holder will bear against theinsulating lining plate for the inside of the front wall of the tank,and bring the holder and the plates therein into a substantiallyvertical plane as defined by the inside of the front wall of the tank.This condition is highly desirable bothduring the cleaning and theplating operations, as it ensures greater uniformity in the electrolyticaction throughout the entire surface of the plate or plates, or in thethrow of the chromium.

The plate holder above referred to is designed particularly for use inthe coating of printing plates or dies wherein the surfaces to becoated-are plane surfaces. Furthermore, in the commercial use of suchmachines, it is desirable to so construct the machine including thetanks and the holder as to permit the coating of a single plate, or thesimultaneous coating of a plurality of plates.

A holder for a machine embodying the invention is so constructed as toensure the effective distribution of the electric current throughout anyor all plates which may be mounted in the holder, irrespective of thenumber of plates. It comprises a sheet metal back plate 31 havingpermanently secured thereto a terminal bar 32 extending well below thecenter of said plate and having a cross-sectional area sufficientlygreat to reduce electrical resistance at this point and afford asufficient capacity to ensure the eflective distribution of the currentthroughout the plate. The end of the terminal bar 32 is provided with abinding post 33, or other means of attachment for a flexible conductorwire thereto. If desired, a handhold of nonconductive material may beattached to the terminal bar through the binding post to facilitate thehandling of the holder, al-

though the current densities used are so low that the use of this handleis a matter of mere convenience. Furthermore, the operators ordinarilyuse rubber gloves.

The face of the back plate 31 opposite to that to which the terminal bar32 is secured, is covered by a plate 35 of vulcanized or other electronon-conductive material, this plate extending from a metallic cleat 36secured adjacent the top edge of the back plate 31, by means of screws,the lower portion of the plate 35 being secured to said plate adjacentthe bottom thereof as by means of screws. The upper portion of saidplate 35 is also secured to said metallic back plate 31 by means ofscrews, thus firmly securing the insulating plate in position. Since noportion of the plate 35 can act either as an anode or a cathode, thedepositing of chromium upon any substantial areaof the holder isprevented, and the flow of electricity and theresultant chemicalreactions are limited to the plates to be coated, or to the clampbarstructure serving the two-fold function of securing the plates inposition upon the holder and conducting the current thereto. Fourvertical lines of openings 37 extend through the metallic back plate 31and the facing 35 of the plate holder, the openings in the metallicbacking being screw-threaded.

Secured in relation to the insulating plate 35 by means of screwspassing therethrough' and through the openings 37 ,is a lower metallicclamp bar 38 which, by reason of the Vertical row of openings 37 may beset at any desired height upon the plate 35, according to the number ofplates to be coated.

Also adjustablv mounted in relation to the back plate 31 and theinsulating facing plate 35'is a. metallic bar 39 which may be secured inany position with relation to the plates 31 and 35 by means of screwsco-operating with the openings 37. Pendant from this bar 39 by means ofheaded studs 40 passing through openings in said bar, is a clamp bar 41,which clamp bar is. capable of sufficient movement with relation to thebar 39 to permit clearance for the insertion and removal of a plate 01'plates from the holder. The clamp bar 41 is acted upon by the clampscrews 42 mounted in the bar 39 and bearing against the top of said bar41. r

The lower clamp bar 38 is in electrical connection with the back plate31 through the screws securing it in position in'relation thereto and tothe facing plate 35. The bar 39 is also in electrical connection withsaid back plate 31 by the screws securing it in position in relationthereto and to the plate 35, the clamp bar 41 beingin electricalconnection through the clamp screws 42 with the bar 39. By using fourscrews for connecting the bars 38 and 39 with the metallic back plate31, an effective distribution of the electric current throughout thesebars is secured, and the use of a plurality of clamp screws 42 will alsohave the same effect with relation to the movable clamp bar 41.

The terminal bar 32 carries a hook 43 by means of which the holder inits entirety may be suspended by the engagement of this hook with theinsulating slab 19 12 or 13 The top plank 18 serves as a support for themotor driven exhauster 23, and also for a double throw pole changingswitch 44.

Associated with the cabinet or housing within which the tanks 10 to 13are contained, is a motor generator set 45 and a swithboard 46 havingtwo switches, one of which 47 controls the circuit to the motor of themotor generator set 45, and the other of which 48 controls the linesfrom the generator of this set.

The contacts of one set of contacts of the switch 48 are connected withthe movable contacts of the switch 44 by the leads 49 and 50respectively.

A detailed description of the switch 44 is unnecessary, as such is oldand well known in the electrical art.

One of the offtake contacts 51 of this switch 44 is in electricalconnection with the bus bar 28, and with the tank 13, by the lead52,.and the other offtake contact 53 is connected by 'means of the lead54 with the terminal bar 32 of the holder.

The door 19 and the top plank18 are provided with cooperating latchmembers 55 and 56 of any desired construction for holding this door inthe closed position.

In depositing .chromium upon the plates, it is desirable, and instripping it therefrom, it is necessary, to have the solution containedin the tanks 12 and 13 at a temperature above normal. To meet thiscondition, I provide a gas heater 60 below the tanks 12 and 13, which isso constructed asto bring and maintain the solution within these tanksto approximately the desired temperatures. These temperatures may rangefrom 110 to 130 F., but any variations from these temperatures would notmaterially modify the operative effects of the machine, provided thatsuch variation is not excessive.

The anodes 30 supported by the bus bar 28 are of pure metallic chromium,and three of such anodes, approximately an inch in width and 12 to 14inches in length, are used. Owing to the extreme hardness of this metal,I have found it highly desirable to provide a special attachment formounting same in relation to the bus bar, this special attachment lit)not only facilitating such mounting of the;

anodes, but also permitting the use of shorter anodes by spacing the topof the anodes away from the bus bar suficiently to cause the submersionof the entire length of the anode in the electrolyte. This attachmentalso firmly holds the anode and acts as a conductor for the electriccurrent passing therethrough. Said attachment comprises a sheet metalyoke 56 secured centrally thereof by means of the bolt 57 to the anode.The inturned ends 58 of this yoke are brought to an edge. Passingthrohgh opposite sides of the 'yoke'is a clamp bolt 59. Notches 30 areground in the opposite edges of the anode adjacent the top thereof,these notches being so formed as to re ceive the reduced ends of theyoke. When these parts are in position, the clamp screw 59 is taken upso as to close the yoke tightly upon the anode, thus firmly holding itin position in relation to the bus bar.

The reduced ends 58 and the notches 30 are used merely to avoid relianceupon frictional engagement of the yoke for suspending the anode in thebath. The material of the yoke is sufficiently flexible to permit theclosing of the sides thereof upon the anode in the manner described, andits cross-sectional area and the area of contact between same and thebus bar, is such as to offer no resistance to the electiigic current inexcess of that of the anode itsel By means of a-chromium plating machinerequires no technical knowledge on the part of the user, but merely thefollowing of a certain prescribed routine.

Water in an amount determined by the dimensions of the tanks 10 to 13 isfirst placed in each of these tanks. Approximately a certain amount ofan alkaline solution proportionate to the water therein, is then pouredinto the tanks 10 and 13. Approximately a certain amount of chromic acidsolution proportionate to the water therein, is then poured into thetank 12. The solution in the tanks 10, 12 and 13 is thefistirredsufficiently to ensure a thorough admixture of the ingredients of thecontents of the tanks. The

baths are immediately in a condition for use and then require no furtherattention over a long period of time, although at intervals of say amonth of two inonths,'approximat ely a certain amount of the chromicacid solution may be added 'to the contents of the tank 12.

'The user of the machine first mounts a plate or plates in the holder,the bars 38 and ll being caused to tightly engage the top and bottomedges of the-plate or ofa roup of plates, as shown in Fig. 4, by takingup the clamp screws 42. This is necessary not only to avoid possibleescape of the plates from the holder to within the bath, but to ensurethe mamas The movable member of theswitch 4A is then thrown so as topositively charge the bus bar 30, and negatively charge the plateholder. The holder with the plates thereon is allowed to remain in thebath of the tank 10 for from three to five minutes, and the holder isthen removed from the tank 10 and dipped in the tank 11, which is a mererinsing tank. After thorough rinsing the holder is removed from the tank11 and immediately placed in the tank 12 with the hook 43 engaging theinsulating slab 12 The door 19 is then closed andlatched, and the holderis allowed to remain in the bath for about an hour.- At the ,expirationof this time, the switch 4:4: is used to out off the flow of current tothe bus bar 28, the door 19 is opened, and the plate holder with theplates thereon is then again submitted to the contents of the tank 11and thoroughly rinsed. The. time intervals stated are not at allcontrolling. N0 harm results if the plates-are left in the tank 10 for alonger interval, and the only result of prolonging the interval duringwhich the plates are in the tank 12, will be an increase in thethickness of the chromium plating. iOne hour in this tank 12 will give aplating .of from .0002 to .0003 of an inch, which is all that isnecessary.

10, 11 or 13, no noxious fumes will be evolved. During the electrolyticaction, however, in the tank 12, there will be a small evolution ofgases from the chromic acid, which, if inhaledby the operator, wouldcause some irritation of themembranes. The use of the door 19, however,coupled with the action of the exhauster 24 through the pipe 23, willremove all these fumes from the housing above the tanks, and at the sametime prevent an operator from attempting to observe the progress of thework, and thus bring his head above the tank 12,'where notwithstandingthe use of the exhauster, he would inhale some of the fumes. While witha proper solution the quantity of such fumes would have no seriouseffect upon the operator, the use of the door 19 eliminates anypossibility of any objectionable characteristics in the use of a machinedue to a theoretical injury to the health of the operators, and makes itpossible to use the machine in a- Workroom occupied by a number ofworkers, without introducing any hazard to which ofiicial objectionmight be raised.

If it be desired to strip thesurfacing from a plate or plates, the sameare mounted in a holder in the manner above'referred to with plates tobe coated, and the holder with the While the plates are in the baths inthe tanks plates is submerged in the solution in the tank 13. The switch44 is then thrown to impress a positive current upon the plate holder,and a negative current upon the tank. The time interval required forstrippingthe plate is but a few minutes.

While I have stated that immediately upon the admixture of the solutionin the tank 12 it is ready for the plating operation, it is desirable toraise the temperature of this solution, and necessary to raise thetemperature of the solution in the tank 13 prior to the platingoperation. The heater 55 is provided for this purpose and thearrangement and capacity of the heater may be such that it will maintainapproximately the desired temperature of these baths.

So far as the machine in its entirety is concerned, no technicalknowledge is required in its operation. The capacity of the motorgenerator set is such as to impress a current of the desired densityupon the holder Whether the same be for cleaning, coating or stripping.The capacity of the exhauster is also predetermined. The various timeintervals are merely approximate intervals which if exceeded will do noharm, and if not reached will not materially impair the efficiency ofthe machine.

A machine embodying the invention has been successfully operated byunskilled men with entirely satisfactory results.

The presence of the insulating lining upon all sides of the tanks 10 and12, and upon thefront and opposite sides of the tank 13, permitscontinued operation of the machine without electrical dilficulties whichwill impair its etficiency inany way.

In fact with a machine embodying the invention, the surfacing of plateswith chromium becomes merely the doing mechanically by the operator ofcertain things for approximately certain intervals, and the repeatedfollowing of the same practices will give substantially uniform results.The solutions used of course may be varied, but with certain solutionsuniform results secured by the machine are assured without any attentionof the operator whatever to the baths beyond the occasional addition ofthe active ingredients of the electrolyte.

The presence of the facing 35 of insulating material will limit thedeposit of chromium upon the plate or plates carried by the holders. Ifonly a single small plate is to be coated, this is of advantage as itnot onlyprevents accretion .of chromium upon the holder with continueduse of the machine, but limits the consumption of the bath to therequirements in coating plates.

Of course the vertical dimensions of the holder must be such as to avoidcontact of the plate 31 with the bottom of the tanks, which are notinsulated since there is no tendency for a short circuiting of thecurrent at this point.

It is not my intention to limit the invention to the precise details ofconstruction shown in the drawings, or to the exact dimensions of thetanks and the plate holder as herein stated, it being apparent that suchmay be varied to adapt the machine to plates of different sizes.

Having described the invention, what I claim as-new and desire .to haveprotected by Letters Patent, is

1. A chromium plating machine embodying therein adjacent tanks adaptedrespectively to receive a cleaning, a rinsing and a plating bath, aholder for articles to be plated, means supporting said tanks with theopen tops thereof at a height to permit the convenient transfer of saidholder from one tank to another, fixed means forming a housing abovesaid tanks having a closed top and an opening at the front thereofthrough which access may be had to said tanks, movable means forclosbath respectively, and means for withdrawing fumes from within saidhousing.

2. A chromium plating machine embodying therein adjacent tanks adaptedrespectively to receive a cleaning, a rinsing and a plating bath,insulating linings extending entirely about the inner walls of the tankscontaining the cleaning and the plating baths, a holder for articles tobe plated, means supporting said tanks with the open tops thereof at aheight to permit the convenient transfer of said holder from one tank toanother, fixed means forming a housing above said tanks having a closedtop and an opening at the front thereof throughwhich access may be hadto said tanks, movable means for closing said opening, a flexibleconductor placing said holder in connection with an electrical source,an insulating slab projecting above the open tops of said tankscontaining the V cleaning and the plating baths, means carried by saidholder adapted to engage said insulating slab and hold the back of saidholder in substantially parallel relation with the insubmerged in saidcleaning bath and said plating bath respectively, and means forwithdrawing fumes from within said housing.

3. A chromium plating machine embodying therein adjacent tanks adaptedrespectively to receive a cleaning, a rinsing and a plating bath,insulating linings extending entirely'about the inner walls of the tankscontaining the cleaning and the plating baths, a holder for articles tobe plated, means supporting said tanks with the open tops thereof at aheight to permit the convenient transfer of said holder from one tank toanother, fixed means forming a housing above said tanks having a closedtop and an opening at the front thereof through which access may be hadto said tanks, a brace bar adjacent and below the open tops of saidtanks, a door hinged upon said brace bar, means for holding said door inthe closed position, a flexible conductor placing said holder inconnection with an electrical source, an insulating slab projectingabove the open tops of said tanks containing the cleaning and theplating baths, means carried by said holder adapted to engage saidinsulating slab and hold the back of said holder in substantiallyparallel relation with the insulating lining of the front wall of thetank, and out of electrical connection with the tank, means insulatingsaid tanks from the means supporting same and from each other, a bus barcommon to, and insulated from, said tanks containing the cleaning andplating baths,'anodes carried by said bus bar and submerged in saidcleaning bath and said plating bath respectively, and means forwithdrawing fumes from Within said housmg.

t. A chromium plating machine embodying therein adjacent tanks adaptedrespectively to receive a cleaning and a plating bath a holder forarticles to be plated, means supporting said tanks with the open topsthereof at a height to permit the convenient transfer of said holderfrom one tank to another, fixed means forming a housing above said tankshaving a closed top and an opening at the front thereof through whichaccess may be had to said tanks, movable means for closing said opening,means insulating said tanks from the means supporting same and from eachother, a bus bar, an anode carried by said bus bar and submerged in saidplating bath,

and means for withdrawin g fumes from within said housing.

In witness whereof I have hereunto afiixed my signature this 20th day ofOctober, 1926.

WILLIAM S. EATON.

